i'm usually testing about 20 months, which for me takes an hour or so...
have you taken a look at the profiling output of the tester?
the general problem with parallelizing the tester is, that many strategies expect a sequential order of the ticks, i.e. they carry some variables or state that gets updated with every tick/bar and is used in computing the actions for the next tick.
you should also check, which version of java you have installed. there are big differences in speed between the updates. the fastest version, i've come across, is the preview-release of java 7, available in sun's (now oracle's) early access program (
https://www.oracle.com/technetwork/java/ ... 42245.html), however, make sure it is stable before using it for anything else but demo-accounts and the historical tester

another way to "speed up" your tests also could be to run them in parallel. so running e.g. 4 times 1 month instead of 1 times 4 months on a quad-core with enough ram. the scaling with that should be nearly perfect.